全文获取类型
收费全文 | 31272篇 |
免费 | 2873篇 |
国内免费 | 1173篇 |
专业分类
耳鼻咽喉 | 118篇 |
儿科学 | 166篇 |
妇产科学 | 189篇 |
基础医学 | 2274篇 |
口腔科学 | 762篇 |
临床医学 | 3541篇 |
内科学 | 1655篇 |
皮肤病学 | 241篇 |
神经病学 | 749篇 |
特种医学 | 752篇 |
外科学 | 1821篇 |
综合类 | 7294篇 |
现状与发展 | 2篇 |
预防医学 | 3765篇 |
眼科学 | 271篇 |
药学 | 5878篇 |
177篇 | |
中国医学 | 5168篇 |
肿瘤学 | 495篇 |
出版年
2024年 | 162篇 |
2023年 | 457篇 |
2022年 | 1163篇 |
2021年 | 1516篇 |
2020年 | 1270篇 |
2019年 | 744篇 |
2018年 | 695篇 |
2017年 | 999篇 |
2016年 | 1117篇 |
2015年 | 1144篇 |
2014年 | 2257篇 |
2013年 | 2244篇 |
2012年 | 2319篇 |
2011年 | 2403篇 |
2010年 | 1829篇 |
2009年 | 1469篇 |
2008年 | 1512篇 |
2007年 | 1748篇 |
2006年 | 1319篇 |
2005年 | 1122篇 |
2004年 | 960篇 |
2003年 | 768篇 |
2002年 | 661篇 |
2001年 | 590篇 |
2000年 | 511篇 |
1999年 | 470篇 |
1998年 | 393篇 |
1997年 | 332篇 |
1996年 | 333篇 |
1995年 | 312篇 |
1994年 | 298篇 |
1993年 | 284篇 |
1992年 | 245篇 |
1991年 | 218篇 |
1990年 | 194篇 |
1989年 | 180篇 |
1988年 | 168篇 |
1987年 | 151篇 |
1986年 | 143篇 |
1985年 | 151篇 |
1984年 | 88篇 |
1983年 | 54篇 |
1982年 | 93篇 |
1981年 | 44篇 |
1980年 | 35篇 |
1979年 | 30篇 |
1978年 | 29篇 |
1977年 | 20篇 |
1976年 | 24篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
When the distance between linked loci is expressed in terms of the correlation between the identity-by-descent (idb) values of the loci, then a path model may be used to order loci with data on sib-pairs and their parents. The relationship between the recombination fraction and the correlation coefficient is developed and a method for fitting a covariance matrix predicted by a specific ordering of loci to an observed covariance matrix is proposed. © 1993 Wiley-Liss. Inc. 相似文献
62.
Abstract – Though the use of mouthguards (MGs) has increased with the increase in sporting activities, little is known about the influence of their fabrication methods on longitudinal dimensional stability. The objective of this study was to compare the difference in the longitudinal dimensional stability between single and laminated MGs. Single-layer MGs were made from a 4.0 mm thick ethylene vinyl acetate (EVA) sheet and laminated MGs were made from two 2.0 mm thick sheets of EVA. MGs were kept in a 37°C water bath for 60 h, equivalent to the time period of 3-months inter-oral use. MG deformation was analyzed by measuring designated points on the MG border using a profile projector (J-12, Nikon Inc., Tokyo, Japan) before and after the water immersion. A finite-element model was also created to examine the time course of stress accumulation during the sheet forming process using Finite Element software. Longitudinal deformation was smaller in the laminated MGs than in the single-layer MGs in the anterior area ( P < 0.05). Finite element method (FEM) analysis also showed the largest stress accumulation in the anterior incisal area where deformations were mainly observed. Laminated double layer MGs have advantages over single-layer MGs in terms of longitudinal stability due to lower stress accumulation during the fabrication process. 相似文献
63.
胆石症是一种常见病,鹅去氧胆酸(CDCA)可用于胆固醇胆石症的治疗。它能改变胆汁组成,降低胆汁内胆固醇饱和度,增加胆固醇溶解性,使胆石逐渐溶解。但CDCA易被肠道内细菌7-脱羟酶作用生成石胆酸(LC),引起腹泄、腹部痉挛、高转 相似文献
64.
C Piérard-Franchimont P Paquet P Quatresooz GE Piérard 《Journal of the European Academy of Dermatology and Venereology》2007,21(5):657-661
BACKGROUND: The observation of photo-exposed skin under ultraviolet light reveals a mosaic pattern of varying intensity in epidermal melanization. Several patterns of mosaic subclinical melanoderma (MSM) have been described using a specially designed CCD camera and the ultraviolet light-enhanced visualization (ULEV) method. Vitamin D(3) and its analogues influence the biology of keratinocytes and melanocytes. OBJECTIVE: To assess the effect of calcipotriol on MSM. METHODS: This randomized split-face study was conducted in 27 men to compare the effect of once daily applications of 5% calcipotriol cream or a moisturizing cream on the heterogeneity of facial MSM. Computerized image analysis of video images was used at 1-month intervals before and during a 2-month treatment, as well as during a 3-month follow-up. RESULTS: At both sites, the average melanin content of the epidermis showed no significant change over time. However, the mottled appearance was smoothened at the calcipotriol site, whereas it was increased at the site receiving the moisturizer. CONCLUSION: The decreased heterogeneity in MSM after calcipotriol applications suggests a control of the epidermal melanocyte unit by the vitamin D(3) derivative. 相似文献
65.
Takuro Yoshikawa Yasuyuki Suzuki Yasuhiro Fujino Keitaro Kakinoki Shiri Li Tadahiro Goto Tomohiro Tanaka Ippei Matsumoto Tetsuya Sakai Yasuki Tanioka Hiroshi Yokozaki Yoshikazu Kuroda 《American journal of transplantation》2005,5(9):2135-2142
Small bowel transplantation (SBT) is associated with a high incidence of infectious complications because of ischemia/reperfusion (I/R) mucosal injury concomitant with potent immunosuppression. In this study, we evaluated whether the cavitary two-layer method (cTLM) could reduce I/R injury and allow early mucosal restoration, particularly after prolonged preservation and transplantation. Canine heterotopic segmental SBT was performed immediately without preservation (group 1), after 24-h preservation in UW solution (group 2) or by the cTLM (group 3). The graft samples were taken 1 h after reperfusion and on days 1, 4 and 7. We assessed graft mucosa with detailed microscopic and electromicroscopic analyses. In Group 3, histological injury and cell apoptosis after transplantation were significantly alleviated and rapidly recovered to a similar level of group 1. The mucosal restoration was morphologically completed within 4 days. In contrast, in group 2, more pronounced mucosal injury and delayed recovery were noted. Crypt cell proliferation activity was well maintained in groups 1 and 3 throughout the experimental period. Our ultrastructural analysis suggested that mitochondrial integrity achieved by the cTLM was a basal mechanism under the prompt mucosal restoration. The cTLM could reduce I/R injury, facilitate mucosal regeneration and restore the nearly normal structure early after SBT. 相似文献
66.
目的:研究中国安氏Ⅰ类错成人与美国安氏Ⅰ类错白人牙颌颅面形态结构的差异。方法:从西安市11所大学2098名新生中选取符合标准的101名(男53名、女48名)安氏Ⅰ类错样本。拍摄头颅定位X线片,用第四军医大学口腔医学院头影测量软件测量,用Alabama分析法与美国安氏Ⅰ类错白人颅颌面测量结果进行比较分析。结果:中国西安地区安氏Ⅰ类错成人上下颌突度大,面型较突;平面倾斜度、上下中切牙倾斜度及下中切牙至NB线距均较大;Y轴相对SN平面夹角增大,生长方向为后下。结论:与美国安氏Ⅰ类错白人比较,中国西安地区安氏Ⅰ类错成人颅面结构呈现颌骨突度大、下切牙唇倾及下颌趋向后下等特征。 相似文献
67.
额、枕部直接冲击导致中脑损伤的力学机制研究 总被引:1,自引:1,他引:0
目的分析额、枕部直接冲击造成中脑应力响应,探讨颅脑直接冲击导致脑干损伤的力学机制。方法构建头颅三维有限元模型,模拟计算额、枕部直接冲击损伤,分析中脑上、下交界面节点应力分布,总结中脑应力响应。结果中脑-间脑界面在冲击初始阶段,2ms即出现应力增高,中脑-桥脑界面应力升高开始于冲击后期(10ms),两交界面节点应力在冲击时程中均持续升高,额部冲击比枕部冲击在中-间脑界面造成的应力峰值高。结论中脑在颅脑直接冲击伤的致伤机制中占有突出地位,中脑的应力改变可解释脑震荡的意识障碍及部分原发脑干伤的临床表现。 相似文献
68.
内眦赘皮与重睑成形同期手术的一种新方法 总被引:12,自引:1,他引:11
目的 探索适合同时行重睑成形术和内眦赘皮矫正术的新方法。方法 根据内眦赘皮深部眼轮匝肌结构上的异常特点,遵循内眦赘皮的上睑(倒向性内眦赘皮除外)内侧睑缘处皮肤短缺和尽量减少局部皮肤瘢痕的原则,设计适合同时行重睑成形术的新内眦赘皮矫正术(反Stallard法)。结果 临床应用86例,进行了为期6个月以上的随访,结果所有患者的重睑为稳定性平行型重睑,内眦已完全或大部分开大,手术效果满意。结论 此内眦赘皮矫正术能够充分矫正内眦部结构上的异常,而且适合与重睑成形术同期施行,是一种效果稳定,结果满意的术式。 相似文献
69.
Cholecystokinin (CCK )isa polypeptidehor monecontaining 33aminoacidsresiduewithgastroin testinal,biliarandbrainactivities Itiswidelydis tributedinthevertebratecentralnervoussystem ,anditcanstimulateextensivelytheliberationofinsulinandglucagonfromtheLangerhansislets GreateffortshavebeendevotedtothesynthesisofCCK 8,itsderivativesandanalogues Amongthedifferentmethods ,theenzymaticmethodisthemosteffectiveonewithmanyadvantagesoverconventionalchemicalmethodologies :enzymespecificitysuppress essid… 相似文献
70.
目的 采用反向Fick氏法和间接测热法测定心脏手术后病人的全身氧耗,并比较两种测量方法的相关性和准确性。方法8例心脏手术术后病人,分别在入ICU后2h和6h时同时采用反向Fick氏和间接测热法测定病人的全身氧耗量。结果 间接测热法和反向Fick法测得氧耗分别是(16±30)ml·min-1·m-2和(127±23)ml·min-1·m-2,前者的测定结果显著高于后者(P<0.01)。相关分析显示两者有较好的相关性(r=0.92,P<0.01)。采用Bland和Altman统计分析提示两种测定结果的平均偏离值为(35.5±13.4)ml·min-1·m-2,其95%的分布范围是(9~62)ml·min-1·m-2,提示两种测量结果间的一致性较差。结论 两种方法测定心脏病人术后全身氧耗的结果有明显差异,其中反向Fick氏法的测定结果误差大、准确性差,而间接测热法是较好的临床选择。 相似文献